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13. Flare Classification in the Era of Global Coverage of the Sun A. Vourlidas, C. Cohen

13. Flare Classification in the Era of Global Coverage of the Sun A. Vourlidas, C. Cohen. The GOES SXR characterization of solar flares has been used widely for 2 solar cycles. But we now have many SEP events associated with far-side flares observed by EUV imagers only (STEREO) .

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13. Flare Classification in the Era of Global Coverage of the Sun A. Vourlidas, C. Cohen

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  1. 13. Flare Classification in the Era of Global Coverage of the SunA. Vourlidas, C. Cohen • The GOES SXR characterization of solar flares has been used widely for 2 solar cycles. • But we now have many SEP events associated with far-side flares observed by EUV imagers only (STEREO). • 360 deg coverage of the Sun will extend until 2019 or so. We invite discussion on the following aspects: • How can we relate those observations to events on the front side or to previous work? • Are EUV imaging observations a suitable proxy for the GOES SXR classification? • Should we use total irradiance or flux integrated over the event only? • Are other quantities (i.e., total emission measure, DEM) better proxies? • Why are there differences in the SXR and EUV light profiles of flares? • Are certain event types (e.g., large flares, SEP-associated, radio-loud or quiet) better correlated in their EUV/SXR profiles? • Which quantity (flare SXR class, rise-to-peak, total duration, etc) is more useful for in-situ and other studies?

  2. Flare-CME Statistics: Flare perspective SXR Peak Intensity vs Flare duration • Kay et al (2003): Flare Study • Flares with CMEs have longer duration, higher peak T, lower rise • Sample: 48 CME, 21 non-CME Flare Rise Time vs Decay Time SXR Peak Temperature vs Peak Intensity

  3. Flare-CME statistics: CME perspective Velocity vs SXR Peak Flux • Vršnak et al (2005): Kinematic study. • No bimodal distribution found (speed or acceleration). • Continuous spectrum of events • Wider CMEs are faster • Weak-flare (B,C) CMEs similar to non-flare CMEs Black: M,X Grey: < M Velocity vs CME Width

  4. The events shown below are some examples of “structured” events. In this family of events, the x-ray signal looks typical, similar to the “classical” flare, but the EUV signal has structure in it. The EUV shape does not follow the x-ray shape, and typically has multiple peaks. Slides provided by D. Mcmullin

  5. Slides provided by D. Mcmullin The events shown on this page show a strong x-ray event with little or no corresponding EUV event. Also to note, the x-ray flare in these events is somewhat slower to peak, peak at a slightly lower value, but last for a relatively long time.

  6. Slides provided by D. Mcmullin In these events, Timing is different between the x-ray event and the EUV event, or the shapes are unusual. The lower right panel shows surprising symmetry in the x-ray signature. Flare Rise Time vs Decay Time

  7. Jan 17, 2010: A case for perpendicular diffusion? No clear anisotropy No clear velocity dispersion Electrons arrive late Courtesy of N. Dresing SPD-2011, A. Vourlidas

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